Ratings of the functioning of client/patients by service providers in mental health service agencies can provide important information to support decision-making within the agency, as well as aid decision-making by funding sources. However, evidence is emerging that these ratings are not detecting changes in the functioning of the chronically mentally ill. This study focuses on differences among rating instruments that affect the ability of rating scales to detect program-induced changes in the functioning of the chronically mentally ill. Expert clinicians will provide similarity judgments of pairings of specially constructed vignettes. Multidimensional scaling analyses of these ratings will indicate which rating dimensions relate most closely to changes in functioning. Ratings of both the vignettes and client/patients will be collected from therapists working in a variety of programs. Widely differing rating instruments will be selected to obtain these ratings. The results will contrast differences in rating instrument construction on five performance criteria: generalizability, sensitivity of the scale to change in functioning of the chronically ill, construct validity, rating completion time, and utility of ratings to therapists. Doubly multivariate analyses of variance will answer whether significant differences exist among scales. Learning which types of rating scales are most sensitive to changes experienced by chronically ill client/patients will enable programs to better document the effectiveness of their treatments.